The present invention relates to a lamp life meter for displaying the remaining life of a lamp that emits light to be provided to an endoscope.
In recent years, endoscopes have been widely used in both medical and industrial fields. Such endoscopes typically include a light-guiding means which guides light emitted from an external light source to the endoscope to the distal end of the insertion section of the endoscope. This light illuminates a body cavity or the inside of a machine to be viewed with the endoscope.
One typical light source is a xenon lamp (or an iodine lamp or metal halide lamp) which is installed in an endoscope light source unit to provide illuminating light to the endoscope. The life of such a lamp is limited and must be replaced after its life expectancy has expired.
To avoid the possibility that the lamp will burn out or generate insufficient light while the endoscope is in use (which would hinder a correct diagnosis), it is necessary to correctly notify the user when the life of the lamp will end. Traditionally, a conducting time counting meter (hereinafter referred to as "lamp life meter") has been used to achieve this result.
FIGS. 16(A), 16(B) and 17 show a traditional lamp life meter 81. FIGS. 16(A) and 16(B) are front and side views of the traditional lamp life meter 81, which is covered with a resin case and has a graded scale 82. The graded scale illustrated in the drawing can count a maximum of 500 hours. A positive input terminal 84 and a negative input terminal 85 extend from the lower part of the main body of the lamp life meter 81 and energize the lamp life meter 81.
FIG. 17 shows the principle of operation of the lamp life meter 81. The traditional lamp life meter 81 includes a glass tube 86 housing mercury 87 and an electrolyte solution 88. When a direct-current voltage is placed between the electrodes (input terminals 84 and 85), mercury 87 is electrolytically extracted from the anode side to the cathode side via the electrolyte solution 88, and the electrolyte solution 88 is moved from the cathode side to the anode side.
Since the distance the electrolyte solution moves is proportional to the quantity of electricity flowing, the total conducting time (i.e., the time that current has been flowing through the lamp and therefore through the terminals 84, 85) can be shown, assuming that a constant current flows through terminals 84 and 85.
With the traditional lamp life meter 81, a circuit is provided in the light source unit to provide a minimal-ampere (15 .mu.A) direct-current voltage, and the light source unit's main body and the lamp life meter 81 are connected with a socket so that it is detachable.
The traditional light source unit's main body has the same structure as the light source unit's main body illustrated in FIG. 2 described below.
The lamp life meter 81 is energized through the lamp-lighting circuit 12 (FIG. 2). When the lamp 11 is lit, a current of approximately 15 .mu.A, which is suitable for driving the lamp life meter 81, is provided to the lamp life meter socket 6a (and/or 6b).
Traditional lamp life meters of the foregoing type have the following advantages:
a. They are easy to use; PA1 b. They are compact; PA1 c. They are relatively low-priced; and PA1 d. They reliably count the conduction time (and therefore the time that the lamp has been lit) and simply display it. PA1 a housing having at least one contact terminal adapted to be coupled to one or more output terminals of said light source, said lamp on signal appearing on one or more of said output terminals when the lamp is on; PA1 a clock generator located in said housing and generating clock signals; PA1 a counter located in said housing and counting said clock signals whenever said lamp or signal indicates that said lamp is on; and PA1 a display mounted in said housing for displaying an indication of the time said lamp has been turned on.
Generally, lamps used for the endoscope light source unit are consumed over time. Additionally, the quantity of light (the quantity of light shot from the distal end of the endoscope) is also reduced over time. Generally, the end of the lamp life means that; there is an unsatisfactory reduction in the quantity of light or that the lamp does not light.
A lamp life meter is traditionally installed on the endoscope light source unit, so that the remaining lamp life can be confirmed before use, and so that the lamp can be replaced with a new one when an insufficient lamp life remains.
While mercury having a high purity of 99.99% is used in traditional lamp life meters, the number of manufacturers producing such high-level mercury has been reduced. Additionally, some of mercury refineries have been closed, making it difficult to procure the required mercury used in traditional lamp life meters.